I can’t access the organization on Microsoft Teams mobile.

Dear @명준 김,

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Based on your description, you can access the organization in Microsoft Teams on desktop, but Teams mobile keeps failing even after removing the account, clearing cache, and reinstalling the app. 

Microsoft Teams on the web uses a more flexible authentication flow: tokens are refreshed more aggressively, and cross-tenant guest redirects are handled more efficiently. In contrast, the Teams mobile app stores tokens locally. As a result, old or conflicting tokens are not always cleared, tenant switching can be more fragile for guest accounts, and Android devices are particularly sensitive to token cache corruption.

In this case, my recommendation is to ask the IT admin of the organization that invited you as a guest to remove and re-add your guest account to check if it can resolve the issue. Also make sure that the Conditional Access policies of the organization aren’t blocking your device.

Besides that, consider adding an additional MFA (Multi-Factor Authentication) method, such as a phone number, to help avoid conflicts with your primary account.

I hope information above meet your expectations. If not, feel free to reach out so I can support you more effectively.

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Access to the organization in Teams mobile depends entirely on successful Microsoft Entra (Azure AD) sign‑in and the organization’s security policies. The context provides only general Teams sign‑in troubleshooting, so the only supported guidance is:

1. Confirm that sign-in to the same organization works on at least one device (desktop or web). If it does not, the organization’s Microsoft 365 tenant or domain may have an issue and only the IT admin can fix it.
2. When Teams shows a banner asking to sign in again, select the banner or sign-in button and complete all required steps, including any multi-factor authentication (MFA) challenges. If the banner reappears, contact the organization’s IT admin.
3. Ensure the device is on any required network (for example, VPN) before opening Teams, and avoid switching networks while using Teams.
4. If Teams still cannot reconnect, try these supported options:
   • Use the Teams web client at https://teams.microsoft.com/ from the mobile browser as a workaround.
   • Uninstall Teams from the device and reinstall it.
   • If using a VPN, toggle it off and on, or temporarily disable it to test.
   • If using Teams for the web, disable any ad blockers.
   • Restart the Wi‑Fi modem.
5. If sign-in continues to fail with an Entra error code (such as AADSTS90023), provide the full error details (Request Id, Correlation Id, Timestamp, and Message) to the organization’s Microsoft 365/Entra administrator. The admin must investigate the sign‑in failure in Microsoft Entra ID and adjust tenant or conditional access settings as needed; end users cannot resolve these directory-level issues themselves.

If access was previously working and suddenly stopped, the most likely causes are:

• The organization now requires a specific network (like VPN) or device compliance to access Teams.
• The organization detected a sign-in risk and is requiring additional verification or a password change.
• The device is no longer compliant with the organization’s policies.

After the admin resolves the Entra sign‑in issue, sign in again in Teams mobile; the banner should disappear and normal access should be restored.

References:

• How to log in to Microsoft Teams
• Why am I having trouble signing in to Microsoft Teams?
• Restore your access to Microsoft Teams
• I can't reconnect to Microsoft Teams